In PHP 4 this PECL extensions
source can be found in the ext/ directory within the
PHP source or at the PECL link above.
This extension is only available if PHP was configured with
--with-dom[=DIR]
. Add
--with-dom-xslt[=DIR]
to include DOM
XSLT support. DIR is the libxslt install directory. Add
--with-dom-exslt[=DIR]
to include DOM
EXSLT support, where DIR is the libexslt install directory.

Windows users will enable php_domxml.dll inside
of php.ini in order to use these functions.
In PHP 4 this DLL resides in
the extensions/ directory within the PHP Windows
binaries download.
A DLL for this
PECL extension is currently unavailable. See also the
building on Windows
section.
Also, there is one additional DLL that must be made available to your
system's PATH in order for this extension to work. In PHP 4 this is
in the dlls/ directory. It's name:
For PHP <= 4.2.0, it's libxml2.dll.
For PHP >= 4.3.0, it's iconv.dll.
And as of PHP 5.0.0, iconv is compiled into your Windows PHP binaries by
default so no extra DLL is needed.